A theoretical study is proposed of the van der Waals attraction involving intermediate to large molecules. The long range goal is to develop reliable techniques for treating inteactions between molecular systems of biological interest. The treatment will be based on the time-dependent Hartree (TDH) approximation which corresponds to an infinite order perturbation treatment and yields results which can readily be programmed for computer use. Preliminary investigations, based on dipolar interaction of linear Drude chains, show that macroscopic continuum formulae or their microscopic equivalents, frequently employed in discussion of forces in biological milieu, yield results which are grossly in error when applied to equilibrium separations. During the initial period of the project attention will be focussed on linear molecules in which the electrons are localized in polarizable units (bonds). First, a formal expression will be developed for the interaction energy based on the full coulomb potential. Then, a detailed computational analysis will be carried out of the effects of quadrupolar interactions, permanent moments, multiple transitions. Next, the treatment will be generalized to linear molecules containing delocalized electrons; computations will first be attempted for model systems (e.g electron gas) and eventually expansion of the coulomb potential can be used at equilibrium distances. Finally, the treatment will be extended to aggregates of molecules.